考虑共因失效的系统可靠性模型

SYSTEM RELIABILITY MODELCONSIDERING COMMON CAUSEFAILURES

不考虑共因失效的影响,求出系统的可靠度表达式,然后将该表达式转化成包含共因信息的可靠度表达式。在模型推导的过程中,直接从系统的失效过程入手,假定构成系统的各元件在独立失效情况下其寿命具有相同的概率分布,构成系统的元件存在多种失效过程,各失效过程相互独立,并服从泊松分布,从系统中某一指定元件的可靠度推广到某指定m个元件均完好的概率。算例解释了该理论模型的使用过程,并将典型系统--串联、并联以及串并联系统的计算结果与不考虑共因失效时系统的可靠度相比较。结果表明,模型的计算结果与传统的定性分析结果相吻合,证明了该理论模型的正确性。

In the presented model, logic relationship of system is constructed and reliability expression of system is obtained with fault tree or block-diagram before considering common cause failure. Then replacing the reliability expression with a new one which includes the effects of common cause failure. To represent common cause failure, the elements are subject to failure by Poisson failure processes that govern simultaneous failure of a specific subset of the elements. The method for calculating the reliability of system requires that a procedure exists for determining system reliability from element reliabilities under the statistically-independent-component assumption. Several examples including typical series system, parallel system and series-parallel system are given to explain how to use the model, and the results are compared with the system reliabilities not considering common cause failures. The results are consistent with the traditional qualitative analysis, which shows the validity of the model.